Duo sewage treatment plant



FIG. 1 is a top view

FIG. 2 is a side view;

FIG. 3 is the other side view;

FIG. 4 is a bottom view;

FIG. 5 is an end view; and,

FIG. 6 is the other end view. 

We claim the ornamental design for the duo sewage treatment plant, as shown. 